Java while loop exception

Question

i'm receiving this error with my java application. I believe the fault is with the add function for my array list. Is there a better way of incorporating this idea without going too complex? (First week of java) Thanks a lot guys!

import java.util.ArrayList;
import java.util.Scanner;


public class PrimeSieve {
    public static void main(int[] args) {
        System.out.println("Enter the max integer(N value): ");
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        System.out.println("Compute prime numbers from 2 to: " + num);
        if(num < 2){
            System.out.println("N must be greater than or equal to 2.");
        }
        else if(num == 2) {
            System.out.println("Prime numbers: 2");
        }
        else {
            ArrayList<Integer> myArr = new ArrayList<Integer>(); 
            int i = 2;
            while(i <= num){
                myArr.add(i);
            }
            System.out.println(myArr);
        }
    }
}

The error -

Exception in thread "main" java.lang.NoSuchMethodError: main

I'm rolling this back to its original form. The edit you put in essentially deleted meat of the question. For the sake of future visitors, it's better to just keep the question in its original form, and let the answers below provide the answer. You should also accept the one that helped you most. — yshavit
– yshavit, Commented Feb 4, 2014 at 0:51

peter.petrov · Accepted Answer · 2014-02-04 00:15:29Z

7

Declare it as public static void main(String[] args)

That will fix it. You currently have (int[] args).

Note that this is not a while loop exception, it is an error
generated at runtime as no proper main method can be found.

See the JLS 12.1.4.: http://docs.oracle.com/javase/specs/jls/se7/html/jls-12.html#jls-12.1.4

edited Feb 4, 2014 at 0:15

answered Feb 4, 2014 at 0:09

peter.petrov

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2 Comments

user2908101 Over a year ago

What I don't understand is the fact that i'm trying to make an arraylist that only holds integers. Wouldn't String[] create an array list that holds strings? Also, do you think you could help me with the Else function as it's not correctly functioning. I'm trying to make a list with integers from 2 to num. (num is the user input #) Thank you.

geoff Over a year ago

@user2908101, please see my response below as there is a way to parse String[] args such that the method can interpret each as an int.

geoff · Accepted Answer · 2014-02-04 00:13:17Z

2

The problem is that the signature of the main method MUST be:

public static void main(String[] args)

You are using int[] args, which unfortunately, is not allowed nor recognized in the main method.

If you really want to interpret the arguments as integers, you can type Integer.parseInt( args[...] ) wherever needed.

answered Feb 4, 2014 at 0:13

geoff

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